1. Field of the Invention
The invention relates to a polyurethane-based adhesive coating or film, and its use, in particular, as a transparent adhesive coating or film in the manufacture of laminated glass panes. More particularly, the invention relates to an adhesive coating or film based on a thermoplastic polyurethane which is resistant to moisture and is formed from moisture-insensitive polyols, aliphatic polyisocyanates, and a specific chain-lengthening agent.
2. Background of the Prior Art
Laminated glass panes are generally used, in particular, in motor vehicles or in architectural applications. Such panes are generally comprised of two sheets of glass and an intermediate layer comprised of a material having energy-absorbing properties, e.g., polyvinyl butyral. Recently a new type of laminated safety glass pane has been described in which the glass sheet disposed toward the interior of the vehicle is covered with a coating or sheet of a material having antilaceration and self-healing properties. The patent publications Fr. Pat. No. 2,308,606 and Eur. Pat. No. 0054491, e.g., describe such a laminated glass pane structure. The film with antilaceration and self-healing properties, which is a heat-setting polyurethane, is attached to the glass sheet by means of an adhesive layer. Fr. Pat. No. 2,398,606 describes the use of a thermoplastic polyurethane as the adhesive layer, in particular a polyurethane formed from a polyester diol. While such is generally satisfactory, it may be said that this type of polyurethane loses part of its adhesiveness with time, and the layer can easily become turbid in severe temperature and humidity conditions, e.g., under prolonged exposure to boiling water.